OEM Lennox Furnace Pressure Switch — 49L91
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The genuine OEM Lennox 49L91 pressure switch is a combustion safety device that confirms adequate venting airflow before your furnace allows ignition. Sensing the vacuum produced by the draft inducer, it proves that exhaust gases are being properly drawn out of the heat exchanger and vented outdoors. Only when the correct pressure is detected does the switch close and permit the burners to light, making it an essential link in your Lennox furnace's safety chain.
Common failure symptoms: The furnace tries to start but locks out, short-cycling, a control board displaying a pressure switch error, or the inducer running without ignition. Cracked hoses, a weak diaphragm, or corroded contacts inside the switch are typical causes of these no-heat conditions.
Why OEM matters: Each Lennox furnace requires a pressure switch set to a precise trip point matched to its venting design. Installing a generic switch with an incorrect rating risks nuisance shutdowns or, worse, unsafe operation. The OEM 49L91 delivers the exact factory calibration, wiring connector, and port configuration your Lennox system demands.
Shipping Information
- Orders placed before 3PM CST ship same business day
- Standard delivery: 2-5 business days
- Express shipping available at checkout
- Free shipping on orders over $75
- Tracking number emailed upon shipment
Return Policy
- 30-day returns on unused parts in original packaging
- Electrical parts (capacitors, contactors, control boards) are final sale once installed
- Email info@nationalhvacparts.com to initiate a return
- Refunds processed within 5-7 business days